1) First you're going to want to use a tool in Terminal called "createinstallmedia" to make your USB drive. Assuming the Install 10.12 Developer Preview.app is in your Applications folder, run this command in Terminal (replacing where necessary, I'd recommend copying and pasting, and then going back and editing):

This could be anywhere between 10 and 30 minutes, but could be more or less depending on your setup.

2) Now run the Clover package. Select the USB as your destination, click Customize and use the following options: "Install for UEFI motherboards" then, under Drivers64UEFI, select "OsxAptioFixDrv-64" and "PartitionDxe-64".

3) Now find that folder of stuff you downloaded earlier. Go to the EFI partition of your USB, and copy and paste CLOVERX64.efi {USB}/EFI/CLOVER. Then copy and paste BOOTX64.efi into {USB}/EFI/BOOT. Then you're gonna wanna copy and paste FakeSMC and any kexts you need for ethernet or wifi into {USB}/EFI/CLOVER/kexts/other.

4) Now boot from your USB! You're gonna wanna use kext-dev-mode=1 and rootless=0 (which are in there by default) and add -v to the end of the boot flags so you can get an output of what's going on.

5) Once you're into the installer, simply install onto your drive.

6) When the install completes, reboot, boot from the USB and this time select your main boot drive that you just installed Sierra onto. Again, boot with kext-dev-mode=1 and rootless=0 (which are in there by default) and -v. It may occur that you have a two part install (like I appear to have), in that case you will just have to reboot a 3rd time.

7) Now you're gonna wanna download and install Clover to your drive using the options we selected earlier. Then copy BOOTX64.efi, CLOVERX64.efi, FakeSMC.kext and your network kext across to the EFI partition on your hard drive. The rest depends on your system, you may need to download some more kexts and drivers, you may now be good to go. Good luck!

UPDATE: Alternative method

Apparently Clover has been updated so it now supports Sierra without having to use the other .efi files.

If you would like to try this new method, you can download the updated Clover here. Then follow the same steps, except ignore the part when you copy the CLOVERX64.efi and BOOTX64.efi files, although you will still need FakeSMC and your ethernet/wifi kexts.